A digital video system allows a multiple system operator (MSO) to deliver television programs and multimedia services to subscribers. The capacity, or bandwidth, of the system determines the programs and services that the MSO delivers. In legacy digital video systems, the MSO sends all of the available programs and services to the subscriber's set-top box on a single cable. Thus, the only way to increase the programs and services available to subscribers in legacy digital video systems is to increase the bandwidth of the cable.
Switched digital video (SDV) systems are an improvement to legacy digital video systems that require less bandwidth to deliver high-bandwidth digital services. SDV systems allow the MSO to send only the content requested by a service group, where each service group includes a set of set-top boxes with visibility to a common set of switched edge devices. To make this possible, the subscriber's set-top box communicates with a network side video server to request the program that the subscriber wants to watch in real-time. The SDV system responds by commanding the edge devices associated with the subscriber's service group to deliver the requested program to the subscriber's service group. Thus, the service group only receives the programs that subscribers in the service group are watching.
Prior art SDV systems encrypt a content stream before it reaches an edge device, typically using a bulk encryption approach. These prior art SDV systems rely on a resource/session manager (e.g., an SDV manager) to command the edge device to receive the encrypted content stream and route it to the appropriate set-top box. Recently, it has become cheaper and more efficient to integrate the encryption function into the edge devices. Since the command from the resource/session manager to the edge device to route a service does not carry the encryption information that the edge device needs, the edge device retrieves the encryption information from a conditional access (CA) system (e.g., an event information scheduler (EIS)). Since every edge device in the SDV system will need to retrieve the encryption information, this creates a possible performance problem at the edge devices because the latency (i.e., time delay) between the channel tune request and the display of the video stream may not meet the subscriber's expectation.
There is a demand for a method and system improving the processing performance at the edge device to avoid an undesirable tuning latency when tuning to a channel in an SDV system. The presently disclosed invention satisfies this demand.